This project deals with the immunobiology and immunogenetics of the HLA system and its clinical applications. Studies are conducted to identify and characterize B cell specific alloantisera and to detect DR antigens and other antigens controlled by linked genes. Of particular significance is a newly defined MB system which is closely associated with HLA-DR. The role of these cell markers in mixed leukocyte culture activation and the generation of cytolytic, memory and suppressor cells is studied. We will also study the effect of MB compatibility on kidney transplant survival. Studies are conducted to define the determinants controlled by the HLA-D locus and their relationship with HLA-DR and MB. Investigations of HLA and disease associations deal with insulin-dependent diabetes of Black patients, acute lymphoblastic leukemia, and ocular histoplasmosis.